Valorization of Lignocellulosic Residues for Cost-Effective Production of Thermo-Alkali-Stable Xylanase by Geobacillus thermodenitrificans X1 of Indian Himalayan Hot Spring

Thermo-alkali-stable and cellulase-free xylanases finds vital applications in pulp bleaching and biomass conversion processes. The objective of the study was to optimize xylanase production by a novel isolate, Geobacillus thermodenitrificans X1. Different physico-chemical parameters were tested for xylanase production by one-factor-at-a-time (OFAT) approach, followed by statistical optimization using response surface methodology (RSM). Various lignocellulosic residues such as wheat straw, rice straw, corn cob and wheat bran were compared with the commercial xylan for xylanase production. The maximum xylanase activity production of 18.5 U/mL was achieved after OFAT optimization at 50 °C and pH 7–8, 200 rpm, after 96 h of incubation time. Subsequently, RSM optimization resulted in 1.3-fold increase in xylanase activity, i.e. 24 ± 2 U/mL. The present study reports the highest xylanase production on lignocellulosic residue (wheat straw) compared to other reported G. thermodenitrificans isolates.